Oxidation reaction process catalyzed by phase-transfer catalyst controlling reaction

ABSTRACT

The present invention relates to an oxidation reaction catalyzed by a reaction controlled phase-transfer catalyst having the general formula of [R 1 R 2 R 3 R 4 N] x H y [A] or Q m MO 3 (L). The catalysts themselves are not soluble in the reaction medium, but can form an active species that is soluble in the reaction medium under the action of one of the reactants. The active species can in turn react selectively with another reactant. When one of the reactants is completely consumed, the catalyst will separated out from the reacting system and can be recovered by means of simple separation method. The recovered catalyst can be recycled with comparable efficiency as that of the original catalyst. The separation of said catalyst is similar to that of heterogeneous catalyst while said catalyst will completely exhibit the characteristics of homogeneous catalyst during the reaction. The catalytic oxidation reaction system is especially suitable for the large-scale industrial production of epoxy cyclohexane from cyclohexene or of epoxy propane from propylene.

TECHNICAL FIELD

The present invention relates to an oxidation reaction process catalyzedby reaction controlled phase-transfer catalyst, in particular, providesa reaction controlled phase-transfer catalyst used in homogeneousoxidation reaction and an oxidation reaction process.

BACKGROUND ART

Catalytic process is the nuclei of modern chemistry and chemicalindustrial application. Based on the morphology of the catalyst in thereaction process, catalytic process can be classed as heterogeneouscatalytic reaction and homogeneous catalytic reaction. At the presenttime, most of the chemical industrial processes employ heterogeneouscatalytic reaction. However, since homogeneous catalytic reaction hasthe advantages of higher catalytic activity of catalyst used and milderreaction conditions, it continuously serves as an important branch infundamental research and industrial applications.

The largest difficulty in the wide application of homogeneous catalyticreaction is that it is difficult to separate and recover the catalystafter the completion of the reaction since the homogeneous catalyst usedis completely soluble in the reacting system [Advances in HomogeneousCatalysis, Chemical Industry Publisher, Beijing, 1990]. Most of thehomogeneous catalysts comprise transition metal that is quite expensiveand therefore the problem of separation and recovery of the catalystwill be the key factor determining the economic suitability of thereaction process.

For the moment, there is not yet systematic method for separating andrecovering catalyst from reacting system for different kinds ofhomogeneous catalytic reactions. Some useful attempts have been made inthis direction, such as loading the homogeneous catalyst on solidcarrier [Catalysis by Supported Complexes, 1981], in which homogeneouscatalyst is loaded on inorganic carriers (such as SiO₂, diatomaceousearth, active carbon etc.) or bonded chemically to organic polymericcarriers (such as chlorine bead of polystyrene series) to form solidcatalyst insoluble in reacting system. By doing so, the catalyst canconveniently be separated and recovered after the reaction ended.However, in this method, the catalytic activity of the homogeneouscatalyst is significantly lowered. At the same time, the metal loaded onthe carrier will easily be fallen off, resulting in the loss of metal.Therefore there had been only a few practical applications.

DISCLOSURE OF THE INVENTION

The objective of the present invention is to overcome the problemgenerally encountered in separation and recovery of homogeneous catalystand to provide a novel reaction controlled phase-transfer catalysttogether with oxidation reaction process carried out using saidcatalyst. The catalyst exhibits completely the characteristics ofhomogeneous catalyst in the reaction process, possesses high catalyticactivity, while it can be separated just like heterogeneous catalystafter the completion of the whole process. The recovered catalyst can berecycled and the performance of the recovered catalyst is comparable tothat of the original catalyst.

The reaction controlled phase-transfer catalyst provided by the presentinvention and used in oxidation reaction along with the oxidationreaction process are characterized in that the catalyst used in thereacting system itself is not soluble in the reaction medium, but underthe action of one of the fed reactants, it forms an active species thatcan dissolve in the reaction medium, and the active species formed reactselectively with another reactant to yield target product; when said oneof the reactants is completely consumed, the catalyst will separate outfrom the reacting system and can be recovered by means of simpleseparation method, and the recovered catalyst can be recycled. Takingoxidation reaction as an example, the overall reaction process can berepresented by the following equation:

where R=H or alkyl group.

Specifically, the oxidation reaction process catalyzed by the reactioncontrolled phase-transfer catalyst of the present invention ischaracterized in that said reaction process comprises the followingsteps:

-   (a) employing a reaction controlled phase-transfer catalyst, wherein    the catalyst itself is not soluble in the reaction medium, but under    the action of one of the reactants, it can form an active species    that can dissolve in the reaction medium, and the active species    react selectively with another reactant to yield target product;    when said one of the reactants is completely consumed, the catalyst    will separate out from the reacting system;-   (b) reacting oxygen source with substrate to yield product in    reaction medium of homogeneous phase or water/oil two phase, under    the catalytic action of the reaction controlled phase-transfer    catalyst;-   (c) separating out reaction controlled phase-transfer catalyst by    centrifugation or filtration after the completion of the reaction,    wherein the catalyst can be recycled; and-   (d) carrying out the oxidation reaction at a temperature of −20° C.    to 110° C.

In the oxidation reaction, said reaction controlled phase-transfercatalyst is characterized in that said catalyst is heteropolyacidcompounds with formula of [R₁R₂R₃R₄N]_(x)H_(y)[A], wherein R₁, R₂, R₃,and R₄ are linear or branched alkyl, cycloalkyl, or benzyl with C₁-C₂₀,or R₁R₂R₃N is pyridine or its homologues; A is a heteropolyanion groupof P or As containing metal atom of Mo, W or V; x is an integer of from1 to 9, and y is an integer of from 0 to 8.

Alternatively, said phase-transfer catalyst can also be a complexrepresented by the general formula of Q_(m)MO₃(L)(II), wherein M is thecentral metal atom such as Mo, W etc.; Q is the cation moiety, such as[R₁R₂R₃R₄N⁺], in which R₁, R₂, R₃, and R₄ are linear or branched alkyl,cycloalkyl, or benzyl with C₁-C₂₀, or R₁R₂R₃N is pyridine or itshomologues; and L is a bidentate ligand containing N or O. When L isN,N-bidentate ligand, it includes R₁,R₂-2,2′-dipyridine (R₁ and R₂ canbe substituents such as H—, C₁-C₂₀ linear or branched alkyl group,cycloalkyl group, aromatic group etc. at the position of 2 to 9), R₁,R₂, R₃-o-phenanthroline (R₁, R₂, and R₃ can be substituents such as H—,C₁-C₂₀ linear or branched alkyl group, cycloalkyl group, aromatic groupetc. at the position of 2 to 9), m=0. When L is N,O-bidentate ligand, itincludes 8-hydroxy quinoline, 2-carboxy pyridine, Schiff base formedfrom salicylaldehyde with primary amine and the like, m=1. When L isO,O-bidentate ligand, it includes β-carbonyl ketone or ester, m=1. Suchcatalysts themselves are not soluble in the reaction medium, but underthe action of oxygen source, they can form oxidated active species thatcan dissolve in the reaction medium. The oxidated active species reactswith another reactant and selectively oxidizes it to target product.When the oxygen source is completely consumed, the catalyst willseparate out from the reacting system and can be conveniently recoveredby simple separation method such as centrifugation or filtration. Therecovered catalyst can be recycled with comparable performance as thatof the original one.

Further, in the reaction controlled oxidation reaction process, thereaction medium used in said reaction includes alcohols such asmethanol, ethanol, n-propyl alcohol, isopropyl alcohol, tertiary butylalcohol and secondary alcohol with branch or dihydroterpineol;paraffinic solvents such as C₅-C₁₈ straight chain alkane, branched chainalkane, or cycloalkane; aromatic solvents such as benzene, toluene,ethyl benzene, xylene, trimethyl benzene or other monosubstituted orpolysubstituted alkyl benzene; ester solvents such as esters ofaliphatic acids, esters of aromatic acids, or trimethyl phosphate,triethyl phosphate, tripropyl phosphate, tributyl phosphate, trioctylphosphate and other trialkyl phosphate; ether solvents such as alkylethers, aryl ethers or aryl alkyl ethers; ketone solvents such asdialkyl ketones, aryl alkyl ketones; nitrile solvents such asacetonitrile, benzyl nitrile; and halogenated hydrocarbon solvents suchas halogenated alkanes and halogenated aromatic hydrocarbons. Thesesolvents can be used alone or in a combination.

In the oxidation reaction, the oxygen source used is hydrogen peroxide(H₂O₂) or alkyl hydroperoxide (ROOH).

In the oxidation reaction, the hydrogen peroxide used is 5% to 90%aqueous solution of hydrogen peroxide; and the alkyl hydroperoxide usedis tertiary butyl hydroperoxide, ethylphenyl hydroperoxide, cumenylhydroperoxide or cyclohexyl hydroperoxide. The aqueous solution ofhydrogen peroxide or solution of alkyl hydroperoxide can be directlyadded as oxygen source.

In the oxidation reaction, when the hydrogen peroxide used is formedin-situ from the oxidation reaction of substituted hydroquinone, afterthe completion of the reaction and separation of the catalyst, productand unreacted raw materials, the substituted hydroquinone could beregenerated by reacting substituted quinone with hydrogen under theaction of hydrogenation catalyst of transition metal.

The substituted hydroquinone used in the reaction process has thefollowing general structure:

wherein R₅ and R₆ are H or C₁-C₁₀ alkyl group. It is also possible touse a mixture of two or more said substituted hydroquinones to generatehydrogen peroxide in-situ.

The hydrogenation catalysts of transition metal are those containingpalladium, platinum, chromium, rhodium, nickel or ruthenium. Thesecatalysts can be prepared by conventional methods.

In the oxidation reaction, the substrate concerned is alkene, alkane,aromatic hydrocarbon, ketone, alcohol, thioether or sulfoxide, and theoxidation reaction taken place is epoxidation of alkene, cleavageoxidation of alkene into aldehyde, ketone or carboxylic acid,hydroxylation of alkane, hydroxylation of aromatic hydrocarbon,oxidation of alcohol into ketone, oxidation of ketone into ester,oxidation of thioether into sulfoxide or oxidation of sulfoxide intosulfone.

The alkene substrates useful in said epoxidation of alkene include thoseorganic compounds having at least one C═C double bond such as aromaticalkenes, aliphatic alkenes, aryl alkyl alkenes, cyclo-alkenes, inear orbranched alkenes, such as propylene, 1-butene, 2-butene, isobutylene,cyclopentene, cyclohexene, styrene etc.; or dienes, trienes andunsaturated compounds containing more C═C double bonds, or unsaturatedpolymers; or derivatives of unsaturated aliphatic acids and their estersor glycerides. Besides alkyl substituents, the alkene substrates canalso contain other substituents, such as halogen, carboxy, ester group,alkoxy, hydroxyl, mercapto, nitro, nitrile group, acyl or amino, withthe examples of chloropropylene, allyl alcohol, phenyl allyl ether. Thesubstrates of the epoxidizing reaction can be used alone or in acombination.

The substrates useful in said cleavage oxidation reaction of alkene intoaldehyde, ketone or carboxylic acid could be in the same range as thatfor the epoxidation of alkene.

The substrates useful in said hydroxylation of alkane include linearalkanes, branched alkanes, cycloalkanes and substituted cycloalkanes ofC₅-C₃₀. The substituents can include halogen, carboxy, ester group,alkoxy, hydroxyl, mercapto, nitro, nitrile group, acyl or amino.

The substrates useful in said hydroxylation of arene include arenes andsubstituted arenes of C₆-C₃₀. Besides the hydrocarbon substituents, thesubstituents also include halogen, carboxy, ester group, alkoxy,hydroxyl, mercapto, nitro, nitrile group, acyl or amino.

The reaction substrates useful in said oxidation of alcohol intoaldehyde or ketone include aromatic alcohols, aliphatic alcohols, arylalkyl alcohols, cycloalkyl alcohols, linear alcohols or branchedalcohols. In addition, glycols could also be oxidized into correspondingaldehydes or ketones.

The substrates useful in said oxidation reaction of ketone to esterinclude aromatic ketones, aliphatic ketones, aryl alkyl ketones, cyclicketones, straight chain ketones or branched chain ketones.

The substrates useful in said oxidation reaction of thioether tosulfoxide include aromatic thioethers, aliphatic thioethers, aryl alkylthioethers, cyclic thioethers, straight chain thioethers or branchedchain thioethers.

The substrates useful in said oxidation reaction of sulfoxide to sulfoneinclude aromatic sulfoxides, aliphatic sulfoxides, aryl alkylsulfoxides, cyclic sulfoxides, straight chain sulfoxides or branchedchain sulfoxides.

In the different kinds of oxidation reaction of the present invention,the reaction conditions are mild and the reaction temperature is in therange of from −20° C. to 110° C., preferably in the range of from 30° C.to 100° C. In addition, the ratio of substrate to hydrogen peroxide oralkyl hydrogen peroxide can be in the range of from 1:100 to 100:1,preferably in the range of from 1:10 to 10:1.

The oxidation reaction process of the present invention is suitable forthe industrial production of epoxy cyclohexane from cyclohexene throughcatalytic epoxidation. The catalyst used is the reaction controlledphase-transfer catalyst that is the above-defined heteropolyacidcompounds. Oxygen source is aqueous solution of hydrogen peroxide orin-situ formed hydrogen peroxide. In organic solvent and in the presenceof the catalyst, cyclohexene is selectively converted into epoxycyclohexane through catalytic epoxidation. The temperature of theepoxidation is in the range of from 30° C. to 100° C.

Furthermore, the present oxidation reaction process is also suitable forpreparing epoxy propane from propylene through catalytic epoxidation.

In addition, the oxygen source used in the epoxidizing reaction processcan be consumed completely during the epoxidation. If residual oxygensource is left after the completion of the epoxidizing reaction, it maybe completely consumed through elevating the system temperature oradding reductive solution in order that catalyst (I) could be separatedand recovered completely to be recycled.

In the case where residual oxygen source is left after the completion ofthe epoxidizing reaction and the treatment of elevating the systemtemperature is employed to consume the excess oxygen source, thetemperature is in a range of 60° C. to 100° C., preferably in a range of70° C. to 90° C.

In the case where residual oxygen source is left after the completion ofthe epoxidizing reaction, it is also possible to add reductive aqueoussolution to the reacting system to treat the excess oxygen source. Thereductive solutions can be dilute aqueous solution of Na₂SO₃, Na₂S₂O₃,NaHSO₃ etc.

The present epoxidizing reaction process is simple and easy to becarried out and can prepare epoxy cyclohexane or epoxy propylene at highefficiency and high selectivity. The used catalyst could conveniently beseparated out, recovered and recycled. In the whole process, onlycyclohexene or propylene, hydrogen peroxide or air and hydrogen areconsumed. The cost of the process is low and the final product isexclusively epoxy cyclohexane or epoxy propane without by-product. Theprocess is simple in the post-treatment and relatively friendly to theenvironment, can meet the technical and economical requirements andsolve the above-mentioned problem of difficulties in separation andrecovery of the homogeneous catalyst. Therefore, the process indeed is anovel approach suitable to produce epoxy cyclohexane or epoxy propane inlarge-scale industry.

As mentioned above, the novel reaction controlled phase-transfercatalyst provided by the present invention can selectively convert awide range of substrates into corresponding oxidized product throughcatalytic oxidation. During the reaction process, said catalyst issoluble in the reacting system and exhibits completely thecharacteristics and action of a homogeneous catalyst. Thus the reactionconditions are mild. After the completion of the whole reaction, thecatalyst will separate out from the reacting system due to lack ofoxygen source. Therefore, separation of the catalyst is similar to thatof the heterogeneous catalyst and the problem of difficulties inseparation and recovery of the homogeneous catalyst is solved. Thepresent process could meet the technical and economical requirements andprovide a novel catalyst system and a reaction process suitable forlarge-scale industrial applications.

Specific Embodiments

The following examples are given to illustrate the present invention inmore detail. Naturally, the present invention is not limited by theseconcrete examples.

EXAMPLE 1 Epoxidation of Cyclohexene

40 mmol of cyclohexene was dissolved in 40 mL mixed trimethylbenzene andthen 20 mmol of 15% (w/w) aqueous solution of H₂O₂ and 0.2 mmol ofcatalyst [(C₂H₅)₂NCH₂Ph]₂HAsMO₂O₁₀ were added. The reaction was carriedout at 65° C. for 1 hour. The conversion of the cyclohexene was 49.0%and the selectivity of the epoxy cyclohexane was 95.2%. At that time,the catalyst separated out from the reacting system and was recovered bycentrifugation and vacuum dried. The unreacted raw material cyclohexeneand the product epoxy cyclohexane were distilled out from the organiclayer. To the residue of the distillation, recovered epoxidizingcatalyst, cyclohexene and hydrogen peroxide were again added and theabove reaction was carried out cyclically. The results of the reactionwere shown in the following table.

The recovered catalyst was used 5 times cyclically and the results wereshown in the following table.

Cycle No. Conversion of Selectivity of of the catalyst cyclohexene %epoxy cyclohexane % fresh catalyst 49.0 95.2 I 48.6 96.0 II 48.2 96.5III 48.7 95.7 IV 48.5 95.8 V 48.6 95.7

When the solvent, oxygen source, catalyst of the reacting system werevaried and the other conditions were identical with those of Example 1,the results obtained from the epoxidizing reaction were shown in thefollowing table.

Selectivity of T Conversion of epoxy Solvent O₂ source Catalyst ° C.cyclohexene % cyclohexane % Tertiary 35% H₂O₂[(C₆H₁₂)(C₂H₅)₂NH]₃[PMo₄O₁₆] 50 45.6 93.7 butanol solution Cyclohexanet-Butyl [(2-C₃H₇)₄N]₂HAsW₂O₁₀ 45 35.8 95.2 hydroperoxide solutionTriethyl Cumenyl [(CH₃ )₃NCH₂Ph]₂HPMo₂O₁₀ 55 46.7 93.1 phosphatehydroperoxide in cumene Phenylmethyl 65% H₂O₂ [δ-C₅H₅NC₄H₉]₇PV₄O₁₆ 3047.9 88.7 ether solution Acetophenone Ethylphenyl [(2-C₄H₉)-(δ- 35 38.982.7 hydroperoxide (C₅H₄N) (C₆H₁₃)]₃[PMo₄O₁₆] solution Benzyl nitrile50% H₂O₂ [(t-C₄H₉)₂N(C₂H₅)₂]₃AsW₂O₁₀ 35 48.6 94.6 solution ChloroformCyclohexanyl [δ-C₅H₅NC₁₂H₂₅]₂HPMo₂O₁₀ 45 49.0 96.8 hydroperoxidesolution

When the solvent, olefin and temperature were changed and the otherconditions were identical with those of Example 1, the results of theepoxidation were shown in the following table.

Selec- Temperature Conversion tivity Olefine Solvent ° C. % %Cyclooctene Methyl t-butyl 30 43 94.6 ether 2-Octene Phenyl methyl 4546.2 95 ether + Toluene Soya bean oil Toluene 60 42.1 95 Styrene o- 4538 92 Dichlorobenzene α- Chloroform 40 40 96.3 Methylstyrene

EXAMPLE 2 Epoxidation of Cyclohexene

20 mmol of 2-methylnaphthoquinone was dissolved in mixed solvent of 15mL dimethyl phthalate and 15 mL diisobutyl methanol and then 2% of 5%Pd/C (w/w) catalyst was added. The reaction was carried out at 6 atm ofhydrogen and 45° C. for 6 hours to hydrogenate 2-methylnaphthoquinone toa degree of 50%. At that time, hydrogenation was stopped and the Pd/Ccatalyst was removed by filtration. Then to the filtrate were added 30mmol of cyclohexene and 0.09 mmol of catalyst [

-C₅H₅NC₄H₉]₇PV₄O₁₆. The reaction was performed at 1 atm of O₂ and 65° C.for 2 hours. At that time, the catalyst had already separated out fromthe reacting system. The conversion of cyclohexene was 33.0% and theselectivity of the epoxy cyclohexane was 98.3%. The catalyst wasrecovered by suction filtration and was dried in air at roomtemperature. The unreacted raw material cyclohexene and the productepoxy cyclohexane were distilled out. To the residue of the distillationwas added 2% of Pd/C (W/W) catalyst, and catalytic hydrogenation wasperformed as described above. Then the recovered epoxidizing catalystand cyclohexene were again added to the system and the above reactionwas carried out cyclically. The results of the reaction were shown inthe following table.

Cycle No. Conversion of Selectivity of epoxy of the catalyst cyclohexene% cyclohexane % Fresh catalyst 33.0 98.3 I 33.1 97.5 II 32.8 97.9 III32.7 97.2 IV 32.8 97.3 V 32.7 97.0

When the solvent, reducing agent and hydrogenating catalyst were changedand the other conditions were identical with those of the Example 2, theresults of the epoxidizing reaction were shown in the following table.

Hydrogenating Conversion of Selectivity of epoxy Solvent Reducing agentcatalyst cyclohexene % cyclohexane % β-methyl Hydrazo-benzene Raney Ni32.8 98.2 naphthalene + trioctyl phosphate 1,3,5- 2-Ethyl Pd/Al₂O₃ 33.396.4 Trimethylbenzene + anthraquinone dihydroterpineol Phenyl methylether + Hydroquinone Pt/Al₂O₃ 29.5 98.7 diethyl phthalate C₉ aromatic2,5-Diethyl Ru/C 24.3 96.8 hydrocarbon + hydrogenated methylcyclohexylacetate pyrazine

EXAMPLE 3 Epoxidation of Cyclohexene

20 mmol of cyclohexene was dissolved in 40 mL of t-butyl alcohol and tothe solution, 40 mmol of 30%(W/W) aqueous hydrogen peroxide and 0.05mmol of catalyst [(CH₃)₃NCH₂Ph]₂HPMo₂O₁₀ were added. The reaction wascarried out at 50° C. for 3 hours. The conversion of the cyclohexene was47.6% and the selectivity of the epoxy cyclohexane was 94.7%. Then 10%Na₂SO₃ aqueous solution was used to decompose the unreacted H₂O₂. Atthat time, catalyst separated out from the reacting system and wasrecovered. Unreacted raw material cyclohexene and product cyclohexanewere distilled out from the organic layer. To the tertiary butyl alcoholobtained from the distillation, the recovered epoxidizing catalyst,cyclohexene and hydrogen peroxide were again added to carry out theabove reaction cyclically.

EXAMPLE 4 Epoxidation of Cyclohexene

40 mmol of 2-ethylanthraquinone was dissolved in a mixture of 19 mL of1,3,5-trimethyl benzene and 17 mL dihydroterpineol. To the solution wasadded 10% Cu/SiO2 (W/W) catalyst. The reaction was carried out at 6 atmof H₂ and 45° C. for 6 hours to hydrogenate 2-ethylanthraquinone to adegree of 50%. Then hydrogenation was stopped and the Pd/C catalyst wasremoved by filtration. To the filtrate, 30 mmol of cyclohexene and 0.2mmol of [(n-C₆H₁₃)₄N]₇PV₄O₁₆ were added successively. The reaction wascarried out at 60° C. for 2 hours and the catalyst separated out fromthe reacting system. The conversion of cyclohexene was 65.3% and theselectivity of the epoxy cyclohexane was 97%. The separated catalyst wasrecovered by filtration and was vacuum dried. Unreacted raw materialcyclohexene and product cyclohexane were distilled out. To the residueof the distillation was added 10% Pd/C (W/W) catalyst and thehydrogenating reaction was carried out at 6 atm of H₂ and 55° C. for 4hours. Pd/C catalyst was then filtered off. To the filtrate, therecovered epoxidizing catalyst and cyclohexene were added to carry outthe above reaction cyclically.

EXAMPLE 5 Epoxidation of Propylene

20 mmol of 2-t-butylanthraquinone was dissolved in a mixture of 15 mL ofmixed trimethyl benzene and 15 mL tributyl phosphate, then to thesolution was added 0.125 g of 5% Pd/C catalyst. The hydrogenatingreaction was carried out at 6 atm of H₂ and 45° C. until 10 mmol of2-t-butylanthrahydroquinone was formed, then the Pd/C catalyst wasfiltered off. O₂ was passed into the mother liquor to complete oxidationto form hydrogen peroxide and 2-t-butylanthraquinone. The oxidizedliquor was transferred into a glass-lined autoclave. 0.09 mmol of [

-C₅H₅NC₁₂H₂₅]₃[PW₄O₁₆] was added and 60 mmol of propylene was chargedinto the autoclave. The reaction was carried out at 50° C. for 4 hours.The conversion of propylene relative to 2-t-butylanthrahydroquinone was90% and the selectivity of epoxy propane was 95%. The separated catalystafter reaction was recovered by centrifugation and was used in the nextreaction. Unreacted propylene, epoxy propane and water were separatedfrom the reacting mother liquor, and 2-t-butylanthraquinone could becatalytically hydrogenated in the presence of 5% Pd/C catalyst to yield2-t-butylanthrahydroquinone again. The results obtained by recyclingcatalyst for 3 times were shown in the following table.

Conversion of Selectivity of Cycle No. propylene (relative epoxy propaneof the catalyst to hydroquinone) % (relative to propylene) % Freshcatalyst 90 95 I 89 93 II 89 94 III 88 91

Other reaction controlled phase-transfer catalysts could also be used tocatalyze the epoxidation of propylene. The results obtained inepoxidizing reaction with other experimental conditions being same asthose used in Example 5 were shown in the following table.

Conversion Selectivity of of ropylene epoxy (relative to propane Treducing (relative to Solvent Catalyst Reducing agent ° C. agent), %propylene), % Toluene + trioctyl [(C₆H₁₂)₄N]₃ 2- 75 40 96 phosphate[PMo₄O₁₆] Ethylanthrahydroquinone Dimethyl [δ-C₅H₅NC₁₆H₃₃]₃2-Butylanthrahydroquinone 55 90 95 phthalate + Triethyl [PW₃O₁₃]Phosphate t-Butyl [(C₂H₅)₃NCH₂Ph]₃ hydrazo-benzene 55 83 91 alcohol[AsW₁₂O₄₀] C₉ Arene + Methyl [(C₄H₉)₃NCH₂Ph]₇ 2,5-Diethyl hydrogenated60 88 88 cyclohexyl [PW₁₁O₃₉] pyrazine acetate Xylene + Dihydroterpineol[δ-C₅H₅NC₁₄H₂₉]₉ 2,3-Diethyl naphthohydroquinone 35 90 82 [AsW₉O₃₄]

EXAMPLE 6 Epoxidation of Olefins

Example 5 was repeated except that solvent, olefin, temperature andreducing agent used to yield H₂O₂ of the reacting system were changed,and the results of the epoxidizing reaction were shown in the followingtable.

T Olefin Reducing agent Solvent ° C. Conversion % Selectivity %Chloropropylene 2-ethylanthrahydroquinone Tripropyl 65 83 81 phosphate +Ethylbenzene 1- 3-ethyl-2- Dimethyl phthalate + 60 85 87 Dodecenemethyl- Toluene + naphthohydroquinone Di-iso-butyl methanol α-2-butylanthra- 1,2- 50 92 90 Naphthylallyl hydroquinone Dichloroethane +Tributyl ether phosphate

Upon the completion of reaction, the catalysts all separated out fromthe system in form of precipitate that could be recovered by simplefiltration or centrifugation and recycled. The reducing agent used inthe reaction was oxidized during the reaction, and could be regeneratedby catalytic hydrogenation after reaction and recycled.

EXAMPLE 7 Oxidation of 2-Butanol for the Preparation of 2-Butanone

40 mmol of 2-butanol was dissolved in 50 mL dichloroethane. To thesolution were added 20 mmol of 35%(W/W) aqueous hydrogen peroxide and0.2 mmol of catalyst [(C₂H₅)₃NCH₂Ph]₂HAsMO₂O₁₀. The reaction was carriedout at 65° C. for 1 hour. The conversion of 2-butanol was 31.0% and theselectivity of 2-butanone was 88.2%. At this time, the catalystseparated out from the reacting system and was recovered bycentrifugation and then vacuum dried. The recovered catalyst wasrecycled 3 times in the above reaction and the results were shown in thefollowing table.

Cycle No. Conversion of Selectivity of of the catalyst 2-butanol %2-butanone % Fresh catalyst 31.0 88.2 I 30.6 89.0 II 31.2 88.0 III 31.788.1

Example 7 was repeated except that the substrate, solvent andtemperature of the reaction system were changed, and the results of theoxidation reaction were shown in the following table.

T Conversion, Selectivity, Alcohol Product Solvent ° C. % % α-PhenethylAcetophenone cyclohexane 55 32.0 92.3 alcohol β-Phenethyl Phenylacet-Acetonitrile 80 20.3 67.9 alcohol aldehyde Cyclohexanol Cyclohexanonet-Butanol 80 30.1 89.3 1-Octanol Octanone t-Butanol 90 26.4 93.3Isobutanol Isobutanone Ethylbenzene 50 30.3 95.6 3-Hexanol 3-Hexanone1,2,3- 55 25.3 92 Trichloropropane

EXAMPLE 8 Epoxidation of 1-Heptene

20 mmol of 2-ethylanthraquinone was dissolved in a mixture of 15 mL ofC₉ arene and 15 mL of methylcyclohexyl acetate. To the solution wasadded 2% of 5% Pd/C (W/W) catalyst. The reaction was carried out at 6atm of hydrogen and 45° C. for 6 hours to hydrogenate2-ethylanthraquinone to a degree of 50%, then the hydrogenation wasstopped and the Pd/C catalyst was removed by filtration. To the filtratewere added 30 mmol of 1-heptene and 0.09 mmol of catalyst[(n-C₈H₁₇)₄N]₂HAsW₂O₁₀. The reaction was carried out at 1 atm of O₂ and65° C. for 6 hours. At this time, the catalyst had separated out fromthe reacting system and the conversion of 1-heptene was 31.0% and theselectivity of 1,2-epoxy heptane was 93.7%. The catalyst was recoveredby suction filtration, dried in air at room temperature and usedcyclically in the above reaction for 3 times. The results of thereaction were shown in the following table.

Cycle No. Conversion of Selectivity of of the catalyst 1-heptene %1,2-epoxy heptane % Fresh catalyst 31.0 93.7 I 31.1 92.5 II 30.8 93.9III 30.7 93.2

EXAMPLE 9 Oxidation of Isoeugenol (1) and trans-Ferulic Acid (2) forPreparing Vanillin (3)

30.5 mmol of 1 or 2 was dissolved in 40 mL of t-butyl alcohol. To thesolution was added 91.5 mmol of 85% H₂O₂ aqueous solution (W/W). Thereacting solution was dried over anhydrous MgSO₄. Then 0.3 mmol (1 mol%) of [(t-C₄H₉)₄N]₃PMo₄O₁₆ catalyst was added. The reaction was carriedout at 60° C. for 2 hours. Both of the conversion of 1 and 2 were 100%and the yield of 3 was larger than 60%. After the unreacted H₂O₂ wasdecomposed by adding 10% NaHSO₃ aqueous solution, the catalyst separatedout from the reacting system and was recovered by centrifugation. Therecovered catalyst was vacuum dried at a temperature below 50° C. andcould be recycled in the above reaction.

EXAMPLE 10 Oxidation of Methyl Phenyl Thioether for Preparing MethylPhenyl Sulfoxide

40 mmol of methyl phenyl thioether was dissolved in 20 mL of chloroform.To the solution was added 10 mmol of 1 mol/L solution of cumenylhydroperoxide in cumene and then 0.1 mmol of catalyst (I). The reactionwas conducted at 0° C. for 2 hours. At this time, catalyst separated outfrom the reacting system. The conversion of methyl phenyl thioether was24.3% and the yield of methyl phenyl sulfoxide was 23.1%. After theseparated catalyst was recovered by filtration and vacuum dried, itcould be recycled in the above reaction.

Example 10 was repeated except that the substrate, solvent, catalyst andreaction temperature of the reacting system were changed, and theresults of the reaction were shown in the following table.

T Conversion, Selectivity, Thioether Solvent Catalyst ° C. % % MethylEthyl [C₁₂H₂₅N(C₂H₅)₃]₃[AsW₄O₁₆] 0 24.8 93 phenyl benzoate thioetherDipropyl Isoamyl [C₆H₁₃N(C₂H₅)₃]₉[AsW₉O₃₄] 20 21.5 88 thioether benzoateMethyl t- n-Octane [(C₄H₉)₃NCH₂Ph]₃[PW₁₂O₄₀] 15 23.3 86 butyl thioetherTetrahydro- Toluene [δ-C₅H₅NC₆H₁₂]₅H₂[AsW₁₁O₃₉] 30 24 92 thiopene

EXAMPLE 11 Oxidation of Sulfoxide for Preparing Sulfone

40 mmol of methyl phenyl sulfoxide was dissolved in 20mL of n-pentane.To the solution was added 20 mmol of 85% aqueous solution of hydrogenperoxide and then 0.1 mmol of catalyst [(n-C₄H₉)₄N]₃[AsW₁₂O₄₀]. Thereaction was conducted at 0° C. for 2 hours. At this time, catalystseparated out from the reacting system. The conversion of methyl phenylsulfoxide was 44.7% and the yield of methyl phenyl sulfone was 40.1%.After the separated catalyst was recovered by filtration and vacuumdried, it could be recycled in the above reaction.

Example 11 was repeated except that the substrate, solvent and reactiontemperature of the reacting system were changed, and the results of theoxidation reaction were shown in the following table.

Conver- Selec- Temperature sion tivity Sulfoxide Solvent ° C. % %Dimethyl sulfoxide Cyclohexane 5 43.2 88 Methyl iso-butyl t-Butanol 1542.3 94 sulfoxide Tetramethylene 1,2- 0 43.5 96 sulfoxide Dichloroethane

EXAMPLE 12 Oxidation of 1-Methylcyclohexene for Preparing n-Enanthicacid-6-one

10 mmol of 1-methylcyclohexene was dissolved in 20 mL of t-butanol. Tothe solution was added 40 mmol of 15% (W/W) aqueous solution of hydrogenperoxide and then 0.05 mmol of catalyst [(n-C₆H₁₃)₄N]₂HPMo₂O₁₀. Thereaction was conducted at 80° C. for 24 hours. The yield of n-enanthicacid-6-one was 90%. Then 10% aqueous solution of NaHSO₃ was used todecompose the unreacted H₂O₂. At this time, the catalyst separated outfrom the reacting system and was recovered by centrifugation and vacuumdried. It could be recycled in the above reaction.

Example 12 was repeated except that the substrate of the reacting systemwas changed and the results of the oxidation reaction were shown in thefollowing table.

Olefin Product Conversion % Selectivity % Cyclohexene Adipic acid 65.468.9 1,2-Dimethyl-1,2- Acetophenone 75.6 82.0 diphenyl-ethylene

Example 13 Oxidation of Cyclohexanone for Preparing Caprolactone

40 mmol of cyclohexanone was dissolved in 40 mL acetonitrile. To thesolution was added 10 mmol of 50% aqueous solution of H₂O₂ (W/W) andthen 0.2 mmol of catalyst [(CH₃)₃NCH₂Ph]₇PV₄O₁₆. After reacting at 25°C. for 28 hours, the catalyst separated out from the reacting system.The conversion of cyclohexanone was 18% and the selectivity of thecaprolactone was 92%. The separated catalyst was recovered byfiltration, vacuum dried and could be recycled to the above reaction.

Example 13 was repeated except that the substrate of the reacting systemwas changed and the results of the oxidation reaction were shown in thefollowing table.

T Conver- Selectivity Ketone Product Oxidizing agent ° C. sion % %Acetone Methyl Cyclohexanyl 60 15 84 acetate hydroperoxide 2-OctanoneHexyl 65% Aqueous 45 13 90 acetate solution of H₂O₂ 4-Methyl-2- Isobutylα-Ethylphenyl 45 16.5 88 heptanone acetate hydroperoxide

EXAMPLE 14 Oxidation of Cyclohexane for Preparing Cyclohexanol andCycloh xanon

To 43 mL of cyclohexane were added 40 mmol of 35% aqueous solution ofH₂O₂ (W/W) and 1 mmol of [N(C₆H₁₃)₄]₅[PV₂O₁₀]. After reacting at 65° C.for 12 hours, the catalyst separated out from the reacting system. Theconversion of cyclohexane was 55% (relative to hydrogen peroxide). Theselectivity of the cyclohexanol was 31% and that of cyclohexanone was57%. The separated catalyst was recovered by filtration, vacuum driedand could be recycled in the above reaction.

INDUSTRIAL APPLICABILITY

The above examples illustrate that in appropriate reaction medium andunder conditions specified by the present invention, catalytic oxidationreaction can be performed at high efficiency and high selectivity usingthe novel reaction controlled phase-transfer catalysts according to thepresent invention. The oxygen source used can be either hydrogenperoxide (H₂O₂) directly added, or hydrogen peroxide produced in-situthrough oxidation reaction in which an oxygen acceptor having reversibleredox properties is used as reducing agent and H₂O₂ can be producedin-situ under the action of air. The reducing agent can be regeneratedfrom its oxidized product through simple catalytic hydrogenation andrecycled. During the oxidation reaction, the catalyst is soluble in thereacting system and exhibits completely the characteristics and actionof homogeneous catalyst, therefore the reaction conditions are mild.After the completion of the whole reaction, oxygen source is completelyconsumed and the catalyst turns to be insoluble in the reacting system,therefore it could be easily separated, recovered and recycled. Inaddition, the oxidation process of the present invention is especiallysuitable for the preparation of epoxy cyclohexane by catalyticepoxidizing reaction of cyclohexene or for the preparation of epoxypropane by oxidation reaction of propylene. In the course of the wholereaction, what are consumed are only cyclohexene or propylene, and H₂O₂or air and H₂, therefore the cost of production is low. The finalproduct is exclusively epoxy cyclohexane without by-product and thus theprocess is friendly to the environment. The reaction process is simpleand easily workable, can meet the technical and economical requirementsand is indeed a novel approach for the large-scale production of epoxycyclohexane or epoxy propane.

1. An oxidation reaction process catalyzed by reaction controlledphase-transfer catalyst, characterized in that the reaction processcomprises the steps of: (a) reacting an oxygen source with a substratein the presence of a reaction controlled phase-transfer catalyst at atemperature of −20° C. to 110° C. in reaction medium of a homogeneousphase or water/oil two phase, to yield a product; and (b) separating outthe reaction controlled phase-transfer catalyst by centrifugation orfiltration after the completion of the reaction, wherein the catalystcan be recycled;  wherein the reaction controlled phase-transfercatalyst is heteropolyacid compounds with formula of[R₁R₂R₃R₄N]_(x)H_(y)[A], wherein R₁, R₂, R₃, and R₄ are independentlyC₁-C₂₀ linear or branched alkyl, cycloalkyl, or benzyl; or R₁R₂R₃N ispyridine or its homologue; A is a heteropolyanion group of P or Ascontaining metal atom of Mo, W or V; x is an integer of from 1 to 9, andy is an integer of from 0 to 8, with the proviso that saidheteropolyacid compounds do not contain active oxygen prior to their usein the oxidation reaction; or a complex represented by the generalformula of Q_(m)MO₃(L), wherein M is a central metal atom selected fromthe group consisting of Mo and W atom; Q is a cation moiety of formula[R₁R₂R₃R₄N⁺], in which R₁, R₂, R₃, and R₄ are C₁-C₂₀ linear or branchedalkyl, branched alkyl, cycloalkyl, or benzyl, or R₁R₂R₃N is pyridine orits homologue; and L is a bidentate ligand containing N or O; when L isN,N-bidentate ligand, it includes R₁,R₂-2,2′-dipyridine (R₁ and R₂ canbe substituents such as H—, C₁-C₂₀ linear or branched alkyl group,cycloalkyl group, aryl group etc. at the position of 2 to 9), R₁, R₂,R₃-o-phenanthroline (R₁, R₂, and R₃ can be substituents such as H—,C₁-C₂₀ linear or branched alkyl group, cycloalkyl group, aryl group etc.at the position of 2 to 9), m=0; when L is N,O-bidentate ligand, itincludes 8-hydroxy quinoline, 2-carboxy pyridine, Schiff base formedfrom salicylaldehyde or substituted salicylaldehyde with primary amineand the like, m=1; when L is O,O-bidentate ligand, it includesβ-carbonyl ketone or ester, m=1.
 2. The oxidation reaction processaccording to claim 1, characterized in that the oxidation reaction isepoxidation of alkene, cleavage oxidation of alkene to aldehyde, ketoneor carboxylic acid, hydroxylation of alkane, hydroxylation of aromatichydrocarbon, oxidation of alcohol to ketone, oxidation of ketone toester, oxidation of thioether to sulfoxide or oxidation of sulfoxide tosulfone.
 3. The oxidation reaction process according to claim 2,characterized in that: the alkene substrates useful in said epoxidationof alkene include aromatic alkenes, aliphatic alkenes, aryl alkylalkenes, cyclic alkenes, linear or branched alkenes having at least oneC═C double bond; dienes, trienes, unsaturated compounds containing moreC═C double bonds, or unsaturated polymers; or derivatives of unsaturatedaliphatic acids and their esters or glycerides, wherein besides alkylsubstituents, the alkene substrates can contain other substituents, suchas halogen, carboxy, ester group, alkoxy, hydroxyl, mercapto, nitro,nitrile group, acyl or amino, and the substrates of the epoxidizingreaction can be used alone or in a combination; the substrates useful insaid cleavage oxidation reaction of alkene to aldehyde, ketone orcarboxylic acid are in the same range as that for the epoxidation ofalkene; the substrates useful in said hydroxylation of alkane includelinear alkanes, branched alkanes, cycloalkanes and substitutedcycloalkanes of C₅-C₃₀, wherein the substituents can include halogen,carboxy, ester group, alkoxy, hydroxyl, mercapto, nitro, nitrile group,acyl or amino; the substrates useful in said hydroxylation of aromatichydrocarbon include arenes and substituted arenes of C₆-C₃₀, whereinbesides the hydrocarbon substituents, the substituents include halogen,carboxy, ester group, alkoxy, hydroxyl, mercapto, nitro, nitrile group,acyl or amino; the substrates useful in said oxidation of alcohol toaldehyde or ketone include aromatic alcohols, aliphatic alcohols, arylalkyl alcohols, cycloalkyl alcohols, linear alcohols or branchedalcohols, and glycols can also be oxidized into corresponding aldehydesor ketones; the substrates useful in said oxidation of ketone to esterinclude aromatic ketones, aliphatic ketones, aryl alkyl ketones, cyclicketones, straight chain ketones or branched chain ketones; thesubstrates useful in said oxidation of thioether to sulfoxide includearomatic thioethers, aliphatic thioethers, aryl alkyl thioethers, cyclicthioethers, straight chain thioethers or branched chain thioethers; thesubstrates useful in said oxidation of sulfoxide to sulfone includearomatic sulfoxides, aliphatic sulfoxides, aryl alkyl sulfoxides, cyclicsulfoxides, straight chain sulfoxides or branched chain sulfoxides. 4.The oxidation reaction process according to claim 1, characterized inthat the reaction medium used includes alcohol solvent selected from thegroup consisting of methanol, ethanol, n-propyl alcohol, isopropylalcohol, tertiary butyl alcohol, secondary alcohol with branch anddihydroterpineol; paraffinic solvent selected from the group consistingof C₅-C₁₈ straight chain alkane, branched chain alkane, and cycloalkane;aromatic solvent selected from the group consisting of benzene, toluene,ethyl benzene, xylene, trimethyl benzene and other monosubstituted orpolysubstituted alkyl benzene; ester solvent selected from the groupconsisting of esters of aliphatic acids, esters of aromatic acids, andtrimethyl phosphate, triethyl phosphate, tripropyl phosphate, tributylphosphate, trioctyl phosphate and other trialkyl phosphate; ethersolvent selected from the group consisting of alkyl ethers, aryl ethersor aryl alkyl ethers; ketone solvent selected from the group consistingof dialkyl ketones, aryl alkyl ketones; nitrile solvent selected fromthe group consisting of acetonitrile, benzyl nitrile; and halogenatedhydrocarbon solvent selected from the group consisting of halogenatedalkanes and halogenated aromatic hydrocarbons, and these solvents can beused alone or in a combination.
 5. The oxidation reaction processaccording to claim 1, characterized in that the oxygen source used ishydrogen peroxide (H₂O₂) or alkyl hydroperoxide (ROOH).
 6. The oxidationreaction process according to claim 5, characterized in that thehydrogen peroxide used is 5% to 90% aqueous solution of hydrogenperoxide; and the alkyl hydroperoxide used is tertiary butylhydroperoxide, ethylphenyl hydroperoxide, cumenyl hydroperoxide orcyclohexyl hydroperoxide.
 7. The oxidation reaction process according toclaim 1, characterized in that the oxygen source used is hydrogenperoxide formed in-situ from substituted hydroquinone, after thecompletion of the reaction and separation of the catalyst, product andunreacted raw materials, the substituted hydroquinone is regenerated byreacting substituted quinone with hydrogen under the action ofhydrogenation catalyst of transition metal.
 8. The oxidation reactionprocess according to claim 7, characterized in that the substitutedhydroquinone used has the following general structure:

wherein R₅ and R₆ are H or C₁-C₁₀ alkyl group, and it is also possibleto use a mixture of two or more said substituted hydroquinones togenerate hydrogen peroxide in-situ.
 9. The oxidation reaction processaccording to claim 8, characterized in that the transition metalhydrogenating catalyst used is those containing palladium, platinum,chromium, rhodium, nickel or ruthenium.
 10. The oxidation reactionprocess according to claim 2, characterized in that said catalyst isheteropolyacid compounds with formula of [R₁R₂R₃R₄N]_(x)H_(y)[A],wherein R₁, R₂, R₃, and R₄ are C₁-C₂₀ linear or branched alkyl,cycloalkyl, or benzyl, or R₁R₂R₃N is pyridine or its homologues; A is aheteropolyanion group of P or As containing metal atom of Mo, W or V; xis an integer of from 1 to 9, and y is an integer of from 0 to
 8. 11.The oxidation reaction process according to claim 2, characterized inthat said catalyst is a complex represented by the general formula ofQ_(m)MO₃(L), wherein M is the central metal atom selected from the groupconsisting of Mo and W atom; Q is the cation moiety of formula[R₁R₂R₃R₄N⁺], in which R₁, R₂, R₃, and R₄ are C₁-C₂₀ linear or branchedalkyl, cycloalkyl, or benzyl, or R₁R₂R₃N is pyridine or its homologues;and L is a bidentate ligand containing N or O; when L is N, N-bidentateligand, it includes R₁, R₂-2,2-dipyridine, wherein (R₁ and R₂ aresubstituents independently selected from the group consisting of H—,C₁-C₂₀ linear or branched alkyl group, cycloalkyl group, and aryl groupat the position of 2 to 9, R₁, R₂, R₃-o-phenanthroline, wherein R₁, R₂,and R₃ are substituents independently selected from the group consistingof H—, C₁-C₂₀ linear or branched alkyl group, cycloalkyl group, and arylgroup at the position of 2 to 9, m=0; when L is N, O-bidentate ligand,it includes 8-hydroxy quinoline, 2-carboxy pyridine, Schiff base formedfrom salicylaldehyde or substituted salicylaldehyde with primary amineand the like, m−1; when L is O, O-bidentate ligand, it includesβ-carbonyl ketone or ester, m=1.
 12. The oxidation reaction processaccording to claim 10, characterized in that said process is catalyticepoxidizing reaction process of cyclohexene for the preparation of epoxycyclohexane, wherein the catalyst is used as reaction controlledphase-transfer catalyst, aqueous solution of hydrogen peroxide orin-situ formed hydrogen peroxide is used as oxygen source, and inorganic solvent and in the presence of the catalyst, cyclohexene isselectively converted into epoxy cyclohexane through catalyticepoxidation at a temperature of from 30° C. to 100° C.
 13. The oxidationreaction process according to claim 11, characterized in that saidprocess is catalytic epoxidizing reaction process of cyclohexene for thepreparation of epoxy cyclohexane, wherein the catalyst is used asreaction controlled phase-transfer catalyst, aqueous solution ofhydrogen peroxide or in-situ formed hydrogen peroxide is used as oxygensource, and in organic solvent and in the presence of the catalyst,cyclohexene is selectively converted into epoxy cyclohexane throughcatalytic epoxidation at a temperature of from 30° C. to 100° C.
 14. Theoxidation reaction process according to claim 10, characterized in thatsaid process is catalytic epoxidizing reaction process of propylene forthe preparation of epoxy propane, wherein the catalyst is used asreaction controlled phase-transfer catalyst, aqueous solution ofhydrogen peroxide or in-situ formed hydrogen peroxide is used as oxygensource, and in organic solvent and in the presence of the catalyst,propylene is selectively converted into epoxy propane through catalyticepoxidation at a temperature of from 30° C. to 100° C.
 15. The oxidationreaction process according to claim 11, characterized in that saidprocess is catalytic epoxidizing reaction process of propylene for thepreparation of epoxy propane, wherein the catalyst is used as reactioncontrolled phase-transfer catalyst, aqueous solution of hydrogenperoxide or in-situ formed hydrogen peroxide is used as oxygen source,and in organic solvent and in the presence of the catalyst, propylene isselectively converted into epoxy propane through catalytic epoxidationat a temperature of from 30° C. to 100° C.